28 April - Watch out for uneven irrigation

Dry pots - Watch out for dry pots within a block. Automatic irrigation systems can be very uneven in distribution if unchecked. Different compost types on the same bed and crops of different size can result in some being over-watered and others under-watered. The best method I know is to check the weight of pots.

Mist - Check the operation of mist systems and replace defective parts. The leaf sensors should have a surface that is clean and flat - light sensors should have a clean "window". Nozzles with last year's algae growth on them can be taken out and put in a tank of Jet 5 to clean them up.

Aquilegia - The very small, green caterpillars of the Aquilegia sawfly can cause widespread defoliation of these plants. If you see any foliage damage, spray outdoor crops with Decis or Toppel 100EC or indoor crops with Nemolt (SOLA 2010-2131) or SB Plant Invigorator immediately. A delay of two days can be too late.

Soil sterilisation - Soil temperatures are warm enough for Basamid applications. The soil must be deeply cultivated and fine to get good control of weed seeds, pests and diseases. Polythene coverings increase vapour intensity. Leave them on until the last possible moment - the soil will remain weed-free for longer.

Conductivity meters - Useful for measuring the level of nutrients in liquid feeds and compost. Take weekly readings to build up a picture of nutrient release of controlled-release fertilisers and optimum growth, using liquid feeding as a top-up. Conductivity is changed by temperature so take measurements at a known water temperature.

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